The CCR-Flow Core is an indispensable resource for NCI and contractor investigators at the Fredereick National Lab for Cancer research. ninety seven investigators from 30 different laboratories have used the expertise of the flow core staff and the instrumentation available and maintained by the staff. The Flow Cytometry Core staff and instrumentation have supported the following studies: sorting support for adaptive immunity of commensals using RAG transgenic mice with a tdtomato fluorescent protein, the role of MDSC's and regulatory T cells in anti-CD40 tumor therapy, the regulation of erythropoiesis of hematopoietec stem cells by Id2 and gfI-1; demonstrating the role of microbiota in autoimmune disease; showing the suppressive activity of CD4+Foxp3+ regulatory T cells by TNFalpha and the homeostatic effects of IKKalpha on these T regulatory cells; role of IFNgamma altering hematopoietic stem cell differentiation in aplastic anemia; studies on the crosstalk of macrophages in Lewis lung carcinoma and the erythroid transcription and Id2 repression of erythroid progenitors. The instruments are used daily by the trained investigators often into the night and on the weekends. The flow core has been training investigators outside of the CIP to analyze their own samples expanding the base of user/operators. This leaves more time for the flow core staff to sort approximately 424 samples and analyze about 8474 samples in the last 10 months of this year. Without the investigators acquiring the data and analyzing their own samples, the government would have to hire full time experienced individuals to perform the same volume of work. At least 13 papers have been published in the past year using data obtained in the flow core. The future goals include keeping up with cutting-edge technology in the flow lab by continuing to expand the pool of investigators trained to run and analyze their own samples to all of CCR in Frederick thereby expanding the use, productivity and quality of the science generated using the core's instrumentation and expertise. We have up-graded all of the instruments so that laser and fluorochrome capabilities are more interchangeable giving investigators the flexability to use more than one instrument. This would prevent loss of data because the instrument needed was in use by another investigator or down because of needed repairs. The cell sorters have also been up-graded to allow direct translation of an experiment developed on an analyzer to the cell sorter to sort out the populations of cells of interest to be further studied. It is critical to have this flexability in analysis of samples as well as for sorting of cells. We would also like to stay a cutting edge facility which would require at least one analyzer to be up-graded to analyze at least 28 parameters at once.